Best Speaker with Krell KAV300i

I know that JM Lab work very good with Krell, but you not only have to look at matching speakers but also match the rest of your gear, as far as speakers go if you can find JM Lab Electra 915.1 or 920.1 second hand, that would be a great match for krell.

Try getting a speaker that has a slightly darker presentation. Bright sounding speakers would not be a good match.
Also stay away from tube friendly speakers like Proac. The Krell will work well with Planar/Ribbon type speakers.

The Martin Logan SL3 mates well with the Krell300i and sells used in this range.

I have used ML Aerius, B&W Matrix 805 and Dynaudio 1.3mkII in the past with this amp. I liked the B&W best.

Martin Logan and B&Ws are the best combos with krell gear. I was just in the factory last week and they had a pair of martin logans in there and they will also tell you B&WS